Method for the production of alkali and alkaline earth metal alkyl carbonates and thiocarbonates



Unite States atent US. Cl. 260455 12 Claims ABSTRACT OF THE DISCLOSURE A method of preparing metal alkyl carbonates and thiolcarbonates comprises reacting an adduct of a tertiary amine, an alkanol and carbon dioxide or carbonyl sulfide with an inorganic metal salt.

The present invention generally relates to organic compounds and to improved methods of preparing the same, and, more particularly, relates to metal alkyl compounds, specifically metal alkyl carbonates, metal alkyl thiolcarbonates, compositions prepared from the same, and improved methods of preparing the metal alkyl compounds, i.e. the metal alkyl carbonates and metal alkyl thiolcarbonates, and compositions containing the same.

Various types of metal alkyl compounds are known and have established uses in industry. For example, the metal alkyl carbonate, sodium methyl carbonate, which has the formula CH OCOONa, is a useful organic intermediate for various synthesis reactions. Various metal alkyl thiolcarbonates can also be used as intermediates in synthesis reactions and the like.

Metal alkyl compounds, such as metal alkyl carbonates and metal alkyl thiolcarbonates, are generally relatively expensive and difiicult to prepare. For example, the sodium-bearing metal alkyl carbonates, such as sodium methyl carbonate, are particularly expensive and somewhat hazardous to prepare by conventional procedures which involve the use of pure sodium metal. Thus, in a conventional procedure for preparing sodium methyl carbonate, methyl alcohol is contacted with metallic sodium (an expensive reagent) to obtain sodium methoxide having the structural formula CH ONa, after which the sodium methoxide is reacted with carbon dioxide to prepare the desired sodium alkyl carbonate. Moreover, metal alkyl thiolcarbonates have similarly proven to be difiicult or impossible to prepare by conventional methods.

In view of the steadily increasing utility of metal alkyl carbonates it would be desirable to provide a simplified yet economical method of preparing various metal alkyl carbonates and also metal alkyl thiolcarbonates, in high yield in a relatively short period of time utilizing a minimum number of method steps and involving inexpensive safe reagents.

Accordingly, the principal object of the present invention is to prepare metal alkyl compounds, specifically metal alkyl carbonates and metal alkyl thiolcarbonates and products thereof, i.e. improved compositions containing metal alkyl carbonates and/or metal alkyl thiolcarbonates.

It is also an object of the present invention to provide improved methods of preparing metal alkyl carbonates and metal alkyl thiolcarbonates.

It is a further object of the present invention to provide an improved method of preparing metal alkyl carbonates and metal alkyl thiolcarbonates from selected adducts in relatively high yield by a simplified inexpensive procedure.

It is another object of the present invention to provide new compositions and methods of preparing the same, said compositions incorporating metal alkyl carbonates and/ or metal alkyl thiolcarbonates.

The foregoing and other objects are accomplished, in accordance with the present invention, by reacting intermediates prepared in accordance with the methods set forth in copending United States patent application, Ser. No. 372,409, entitled, Organic Compounds and Method of Preparing the Same, filed June 3, 1964, now abandoned, and application Ser. No. 592,749, filed Nov. 8, 1966, of which the inventors are the same as for the present application, and so also is the assignee, with selected reagents to derive the desired metal alkyl carbonateor thiolcarbonate-containing products, specifically metal alkyl carbonates and metal alkyl thiolcarbonates. Such methods are simple, direct, inexpensive and relatively rapid and provide a relatively high yield of the desired metal alkyl carbonate or metal alkyl thiolcarbonate.

As a specific example, trimethyl amine is dissolved in absolute methanol and the resulting mixture is then contacted with carbon dioxide gas by bubbling the gas therethrough for a period of about one-half hour at about 50 C. at atmospheric pressure until carbon dioxide is no longer absorbed. Trimethyl ammonium methyl carbonate is found to be present in a substantial concentration in the solution. This compound is believed to have the structural formula C11 0 C O (CH3)3NH The trimethyl ammonium. methyl carbonate is then converted into sodium methyl carbonate by treating the trimethyl ammonium methyl carbonate-containing metha nol solution with a suitable concentration of methanolsoluble sodium hydrosulfide, NaSH. After this treatment, sodium methyl carbonate precipitates from the methanol solution of trimethyl ammonium hydrosulfide and is obtained in purified condition by filtration. The solution is then refluxed to decompose the trimethyl ammonium hydrosulfide to trimethyl amine and hydrogen sulfide, the latter passing from the solution as a gas.

Thus, in accordance with the present invention, an intermediate or adduct, which is formed at low temperature from a selected tertiary amine, a selected alkanol and carbon dioxide, can be reacted with a suitable metallic salt soluble or dispersible in the alkanol or in a mutual solvent to provide the desired metal alkyl carbonate. In like manner, an intermediate formed from a low temperature reaction between a selected tertiary amine, a selected alkanol and carbonyl sulfide can in turn be reacted with a suitable metallic salt dispersible or soluble in the alkanol or in a mutual solvent to provide desired metal alkyl thiolcarbonates.

As more particularly set forth in the aforesaid copending United States patent applications Ser. Nos. 372,409 and 592,749, the tertiary amine which is used to form the intermediate or adduct is any tertiary amine capable of readily reacting with the selected alkanol and the carbon dioxide or carbonyl sulfide to form the adduct. Preferably, the tertiary amine is of a relatively low molecular weight and capable of being readily dispersed or dissolved in the alkanol. Non-limiting examples of suitable tertiary amines are the following: trimethylamine, triethylene diamine, also known as 1,4-diazobicyclo (2.2.2) octane, or DABCO, l-azabicyclo (3.3.1) nonane, l-azabicyclo (2.2.2) octane, triethylamine, tri-n propylamine, dimethyl ethylamine, dimethyl propylamine, dimethyl benzylamine and pyridine.

The alcohol utilized in reacting with the tertiary amine and carbon dioxide or carbonyl sulfide to form the intermediates which are the starting materials for the present method, is any suitable alkanol sufficiently reactive with with the tertiary amine and carbon dioxide or carbonyl sulfide to form the desired adduct. Such adduct should be, as previously indicated, one from which the desired end products, that is, the metal alkyl carbonates or metal alkyl thiolcarbonates, can be readily obtained. Non-limiting examples of suitable alkanols include the following: methanol, ethanol, iso-propanol and propanol. Usually, the alkanol includes no more than about 3 carbon atoms and is present in excess concentration when utilized in forming the adduct and in forming the metal alkyl carbonate or metal alkyl thiolcarbonate from the adduct, Thus, for example, at least one mol of the alkanol contributes to the formation of one mol of the adduct. Additional amounts of the alkanol are needed when the alkanol acts as a solvent or dispersant for the adduct-forming system and also for the metal alkyl carbonateor metal alkyl thiolcarbonate-forming system. The adduct-forming third reagent is selected from the group consisting of carbon dioxide and carbonyl sulfide and can be used in either the gaseous or in the liquid form. Such reagent usually is slowly bubbled through the other constituents as a gas at relatively low temperature, as in a stirred autoclave or the like. The temperature does not ordinarily exceed about 50 C. and preferably does not exceed about 30 C. The methods of formation of the described adducts are more particularly set forth in the aforesaid copending United States patent application, Ser. Nos. 372,409 and 592,749 and, accordingly, will not be described further herein.

It will be understood that it is a part of the present invention to utilize the COS-containing adducts and the CO containing adducts formed as previously described in the preparation of metal alkyl derivatives of carbonates and thiolcarbonates. The adducts can be generally characterized as ammonium carbonate-containing compounds having the general formula where A is CO or COS and R, R', R" and R are radicals, specifically the groups R, R and R" are radicals, preferably alkyl radicals of a tertiary amine and R is an alkyl radical derived from an alkanol.

The adduct, in accordance with the present invention, is reacted with a selected inorganic compound of the metal of the desired end product. The adduct is reacted while dissolved or dispersed in the alkanol from which the adduct was formed and/or another solvent or dispersant therefor and, preferably, for the alkanol, if present. The adduct may be present in any suitable concentration in the solvent or dispersant. The inorganic compound is one which is soluble or at least readily dispersible in the alkanol and/or any other solvent or dispersant present with the adduct. The compound also must be one which reacts with the adduct in the following manner:

where R, R, R and R', and A are as previously described, X is the desired metal cation and Y is a suitable anion. Typical inorganic salts or other compounds suitable for the present purposes include the following: sodium hydrosulfide, calcium chloride, magnesium chloride, calcium hydrosulfide, lithium chloride, potassium chloride, potassium hydrosulfide, strontium sulfide and beryllium chloride. Other inorganic salts and the like can be used, provided they meet the foregoing criteria. The salts or other suitable compounds can be used in any suitable concentration, for example, in an approximate 1:1 mol ratio with the adduct.

Solvents or dispersants for all the components, e.g. the alkanol, if any, and the adduct and inorganic salt or compound may comprise, for example, acetone when the alkanol is methanol, when the inorganic salt is calcium chloride and the adduct contains only alkyl groups of not more than 3 carbon atoms each. Other solvents found suitable in many instances are the following: dioxane, ethyl methylketone and butanol.

The following specific examples more particularly set forth certain features of the present invention:

Example I The adduct of triethyl ammonium o-methyl carbonate is formed in about yield by reacting 101 gm. of anhydrous triethyl amine with dry CO at 30 C. in an excess of absolute methanol (300 cc.). The adduct has the following structural formula:

0 ll CHaO C ONICzHslZH This adduct, while still dissolved in the methanol, is then reacted with a selected anhydrous methanol-soluble inorganic salt to obtain the desired metal alkyl carbonate. Thus, the reaction is carried out by pouring a solution of 200 gm. of anhydrous methanol-soluble calcium chloride (CaCl in 300 cc. of methanol into the adduct solution and allowing the reaction to continue for a period of 30 minutes at 30 C. The reaction is substantially complete with an essentially yield, and is characterized as follows:

zomoooowinnafin CaCh [CHaOCOObCa ZlCzHslsN ZHCl The reaction products are then subjected to filtration to separately recover anhydrous calcium methyl carbonate, (CH OCOO) Ca, hydrochloric acid and triethyl amine. The amine can thereupon be reutilized in the preparation of additional amounts of the adduct after neutralization. The calcium methyl carbonate so obtained is in discrete finely divided particulate form. It is useful in chemical syntheses and, when contacted with Water it breaks down to methanol, calcium carbonate and carbon dioxide so that it is useful as an antiseptic, disinfectant and the like.

Example II The same procedure as that of Example I is carried out, but utilizing 100 gm. of anhydrous trimethyl amine dissolved in 400 cc. of absolute methanol. This solution is contacted with gaseous CO (by bubbling therethrough) at 25 C. for 40 minutes. Trimethyl ammonium methyl carbonate in a yield of about 90% is thereby prepared. This adduct remains dissolved in the methanol while it is contacted at 25 C. with 200 gm. of anhydrous calcium chloride in 300 cc. of methanol. Thus, the calcium chloride-methanol solution is merely slowly added to the adduct-containing methanol and the trimethyl ammonium methyl carbonate is substantially completely converted in a short period of time (less than 15 minutes) into calcium methyl carbonate which product is separately recovered from the solution by filtration.

Example III The adduct trimethyl ammonium o-methyl thiolcarbonate having the formula is formed by reacting gm. of anhydrous trimethyl amine, while dissolved in 400 cc. of absolute methanol, with anhydrous COS gas by bubbling the COS through the solution at 30 C. for 45 minutes until the reaction is complete. The desired adduct, trimethyl ammonium o-methyl thiolcarbonate is obtained in about 80% yield. It is allowed to remain in the methanol solution while it is contacted at 20 C. with 200 gm. of anhydrous CaCl in 300 cc. of methanol, the latter being slowly added to the solution, whereupon the trimethyl ammonium o-methyl thiolcarbonate is substantially completely converted (90%+ yield) almost immediately (within about 10 minutes) to calcium methyl thiolcarbonate having the formula (CH OCOS) Ca, a product insoluble in the methanol and separately recovered therefrom by filtrattion. The calcium methyl thiolcarbonate is useful as a chemical intermediate in a wide variety of chemical reactions.

Example IV In run A, anhydrous trimethylamine is dissolved in 59 gm. amount in 300 cc. of absolute ethanol and reacted With dry CO gas bubbled the'rethrough for 25 minutes at 25 C. The product, trimethyl ammonium o-ethyl carbonate,

c.1150 d omonmfi is obtained at about 90% yield and, while still dissolved in the ethanol, is then reacted with 90 gm. of CaCl in 300 cc. of ethanol by direct addition of the CaOl solution thereto with stirring at 25 C., to produce within 20 minutes a 90%+ yield of calcium ethyl carbonate, Ca(C H OCOO) This desired product is insoluble in the ethanol and is filtered from the other reaction products, namely, HCl and trimethyl amine and other constituents in the ethanol. Calcium ethyl carbonate has the property of breaking down into ethyl alcohol, carbon dioxide and calcium carbonate upon exposure to water, so that it could be effectively used as an antiseptic, disinfectant and the like for direct application to the skin in the dry form. Alternatively, it can be contacted with Water to yield ethyl alcohol.

In run B, carried out in the same manner as run A, except that dry COS gas is substituted for the CO gas, trimethyl ammonium o-ethyl thiolcarbonate,

is formed in a yield of about 95% of theoretical and then is converted, while still dissolved in the ethyl alcohol, at a yield of about 90% to calcium ethyl thiolcarbonate, Ca(COSOC H by the previously described procedure. The product is separately recovered from the ethanol as a powder, useful as a chemical intermediate.

In run C, carried out in the same manner as run A, except that 200 gm. of NaSH (anhydrous) are substituted for the CaCl the final product, sodium ethyl carbonate, NaOOCOC H is isolated by filtration. Refluxing the reaction product mixture which contains trimethyl ammonium hydrosulfide decomposes the same to trimethyl amine and H 8 gas, the latter passing from the solution. Pure sodium ethyl carbonate is obtained in a yield of about 85% of theoretical. The sodium ethyl carbonate is recovered as a white powder which decomposes upon contact with water to form sodium bicarbonate and ethyl alcohol. Accordingly, it is useful as a disinfectant, germicide, sterilizing agent, alkaline neutralizer and the like.

Example V Anhydrous tripropyl amine in 143 gm. amount is dissolved in 300 cc. of absolute methanol and dry CO is bubbled therethrough at 35 C. for one hour to produce tripropyl ammonium o-methyl carbonate,

in about 95 of theoretical yield. This product in methanol is then reacted with 56 gm. of anhydrous NaSH in 300 cc. of methanol at 30 C. by adding the NaSH in the methanol slowly to the adduct solution, after which the mixture is subjected to filtration to obtain about 90% of theoretical yield of sodium methyl carbonate, CH OCOONa.

In a parallel test, the same reactions are carried out, except that anhydrous COS gas is substituted for the CO so that tri-propyl ammonium o-methyl thiolcarbonate,

is initially obtained as the adduct in a yield of about 90% of theoretical. This adduct is then converted to 6 sodium methyl thiolcarbonate, CH OCOSNa, in a yield of about of theoretical. The sodium methyl thiolcarbonate is a valuable intermediate for synthesis reactions.

Example VI In run A, anhydrous triisopropyl amine is 150 gm. amount is dissolved in 400 cc. of absolute isopropanol, then contacted at 25 C. for 1 hour with dry CO gas by bubbling the latter therethrough. The product, triisopropyl ammonium o-isopropyl carbonate,

onmoaooooNuoHmoHhfI is obtained in over 75% yield and is decomposed in the isopropanol by reaction with 250 gm. of anhydrous CaCI the latter being added thereto with stirring, to provide a substantial yield of calcium isopropyl carbonate, Ca(OOCOCH(CH a compound useful in organic synthesis and as a disinfectant and sterilizing agent, since it breaks down to isopropyl alcohol, calcium carbonate and carbon dioxide upon contact with water. The calcium isopropyl carbonate is recovered by filtration.

In a parallel test, run B, 250 gm. of anhydrous NaSH are substituted for the CaCl and the product, sodium isopropyl carbonate, Na(OOCOCI-I(CH is recovered in high yield. Such product is useful in organic syntheses.

In two further parallel runs, runs C and D, the conditions of runs A and B, respectively, are duplicated, except that anhydrous COS gas is substituted for the C0 The adduct so formed in runs C and D is triisopropyl ammonium o-isopropyl thiolcarbonate,

The product of run C is calcium isopropyl thiolcarbonate, Ca(COSOCH(CH an intermediate useful in various chemical reactions, and is obtained in a substantial yield. The product of run D is sodium isopropyl thiolcarbonate, NaCOSOCI-I(CH an intermediate useful in chemical reactions such as synthesis, and is also obtained in a substantial yield.

Example V-II In run A, 100 gm. of anhydrous trimethylamine is dissolved in 500 cc. of absolute methyl alcohol, then contacted at 25 C. for 15 minutes with dry CO gas by bubbling the gas therethrough at atmospheric pressure. The product is the adduct trimethylammonium methyl carbonate of the formula and is obtained in over 95 of theoretical yield. It remains dissolved in the methyl alcohol and is contacted therein at 25 C. in the methanol with 150 gm. of anhydrous magnesium chloride in 300 cc. of methanol and reactive therewith to form magnesium methyl carbonate, the desired product, in a yield of about 95% of theoretical over a period of 10 minutes. The magnesium methyl carbonate is utilized in solution since it is soluble in the methanol. It is useful as carboxylating agent and chemical intermediate.

In run B, the conditions of run A are duplicated, except that 150 gm. of another inorganic salt, calcium sulfide, are substituted for the inorganic salt used in run A. The desired calcium methyl carbonate is obtained in of theoretical yield and is separately recovered by filtration.

In runs C .and D, the conditions of runs A and B, respectively, are duplicated, except that anhydrous COS gas is substituted for CO In run C, the adduct trimethylammonium methyl thiolcarbonate of the formula CHaO C OS-(C 111031313:

is obtained in a yield of 90% of theoretical and is converted to the desired thiolcarbonate, magnesium methyl thiolcar-bonate, of the formula Mg (OCSO'CH in a yield of of theoretical. Such carbonate is soluble in methanol, and is used as a thiolcarboxylating agent in solution. In run D, the desired final carbonate product is again calcium methyl thiolcarbonate of the formula Ca(OCOS CH and is obtained in 95% of theoretical yield.

Example VIII In run A, 100 gm. of anhydrous triethylene diamine (DABCO) is dissolved in 300 cc. of absolute methyl alcohol, then contacted at 25 C. for 10 minutes with dry CO gas by bubbling the gas therethrough at atmospheric pressure. Only one of the amine groups in the DABCO is protonated and the product has the formula and is obtained in over 95% of theoretical yield. It remains dissolved in the methyl alcohol and is contacted therein at 25 C. with 200 gm. of anhydrous calcium chloride dissolved in 300 cc. of methyl alcohol and re active therewith to form calcium methyl carbonate, the desired product, in a yield of about 95 of theoretical over a period of 10 minutes. The calcium methyl carbonate is recovered separately by filtration.

In run B, the conditions of run A are duplicated, except that 200 gm. of another inorganic salt, potassium chloride, are substituted for the inorganic salt used in run A. Moreover, the desired metal alkyl carbonate, potassium methyl carbonate having the formula KOCOOCH is obtained in 95 of theoretical yield and is separately recovered by filtration. 'It is a white powder and is useful as a chemical intermediate.

It will be understood, therefore, that the present method incorporates the use of adducts of selected tertiary amines, alkanols and COS or CO to provide metal alkyl carbonates (in the case of CO or metal alkyl thiolcarbonates (in the case of COS) by reaction with selected inorganic salts and similar compounds. The metal alkyl carbonates and thiolcarbonates formed in accordance herewith are useful for a variety of purposes in addition to those heretofore specified. For example, those compounds which contain metals which are catalytic in action can be used as carriers for such metals. Decomposition of certain of those compounds, for example by reaction with Water in the case of selected metal alkyl carbonates, results in the release of inorganic salts bearing the catalytic metals for deposition, etc.

Moreover, calcium ethyl carbonate and sodium ethyl carbonate prepared by the present method have special further utility. Thus, their use in mixtures with other constituents forms a part of this invention. In this regard, calcium ethyl carbonate has the structural formula [C H OCOO] Ca and can be prepared as previously described. Such product can be provided in powder form which breaks down upon contact with water to form ethyl alcohol and calcium carbonate and to release carbon dioxide as gas bubbles. This reaction can be characterized as follows:

[C H OCOO]gCa+H O 2C H OH+CO+CaCO Metal alkyl carbonates in dry powder form prepared by the present method, which readily decompose and release bactericidal or sterilizing alcohols upon contact with water can be used in dry medicinal formulations,

alcohols and harmless materials, such as calcium carbonate, sodium bicarbonate, carbon dioxide and the like, include calcium ethyl carbonate, sodium ethyl carbonate, potassium ethyl carbonate, magnesium ethyl carbonate, and the like.

Accordingly, the above examples clearly illustrate that metal alkyl carbonates and metal alkyl thiolcarbonates of the indicated types can be readily prepared by a new inexpensive method. Certain of said metal alkyl carbonates and/or metal alkyl thiolcarbonates are believed to be wholly new compounds.

What is claimed is:

1. The method of preparing metal alkyl compounds selected from the group consisting of metal alkyl carbonates and metal alkyl thiocarbonates, which method comprises reacting an adduct of a tertiary hydrocarbyl amine of from 3 to about 9 carbon atoms, an alkanol having no more than about 3 carbon atoms and a reagent selected from the group consisting of carbon dioxide and carbonyl sulfide, said adduct consisting of said tertiary amine, said alkanol and said reagent, with an inorganic alkali or alkaline earth metal salt in the substantial absence of water, whereby the said metal alkyl compound is formed.

2. The method of claim 1 wherein said alkanol is selected from the group consisting of methanol, ethanol and isopropanol.

3. The method of claim 1 wherein said tertiary amine is selected from the group consisting of trimethyl amine, triethyl amine, tripropyl amine, triisopropyl amine and triethylene diamine.

4. The method of claim 1 wherein said metal salt is selected from the group consisting of chlorides, sulfides and hydrosulfides.

5. The method of claim 4 wherein the metal of said metal salts as selected from the group consisting of sodium, potassium, calcium and magnesium.

6. The method of claim 1 wherein said adduct and said salt are at least substantially uniformly dispersed in a dispersing medium during said reaction.

7. The method of claim 6 wherein said metal alkyl compound is metal alkyl thiolcarbonate and said reagent is carbonyl sulfide.

8. The method of claim 6 wherein said metal alkyl compound is a metal alkyl carbonate, and wherein said reagent is carbon dioxide.

9. The method of claim 8 wherein said metal alkyl carbonate is a metal ethyl carbonate which decomposes upon contact with water to form ethyl alcohol and a carbonate-type compound.

10. The method of claim 9 wherein said carbonate-type compound is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, magnesium carbonate and calcium carbonate.

11. The method of claim 9 wherein said metal is sodium, wherein said inorganic metallic salt is sodium hydrosulfide and wherein said adduct is reacted while dissolved in excess ethanol, the sodium hydrosulfide being added thereto to form the metal alkyl compound, sodium ethyl carbonate.

12. The method of claim 9 wherein said metal is calcium, wherein said inorganic salt is calcium chloride and wherein said adduct is reacted while dissolved in ethanol, the calcium chloride being added thereto to form calcium ethyl carbonate.

References Cited UNITED STATES PATENTS 2,841,525 7/1958 Birum et a1. 260455 XR CHARLES B. PARKER, Primary Examiner.

D. R. PHILLIPS, Assistant Examiner.

U.S. Cl. X.R. 

